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Vitamin C has been touted as a remedy for everything from wrinkles to cancer to colds. The idea that vitamin C is an immune system booster is not new, but the evidence behind the claim is conflicting. Bottom line: Vitamin C is not a silver bullet for the common cold, but it could have some potential benefits for those suffering from the stuffiness, sore throat, and general misery of a cold.

Just What Is Vitamin C?

Vitamin C, also known as L-ascorbic acid, is a vitamin that's essential for the growth and repair of tissues throughout the body, including the gums, cartilage, and skin. Vitamin C is water-soluble, which means it dissolves in water. It is not stored in the body and must be replaced each day. In addition to being found naturally in many foods, such as citrus fruits, tomatoes, and broccoli, it is widely available as a dietary supplement.

Some potential benefits of vitamin C remain unclear. Researchers are investigating whether this potent antioxidant can actually help prevent or delay cancer and heart disease, for instance, by reducing the damage caused by free radicals. That's in addition to decades-long endeavors by scientists trying to determine whether vitamin C could actually help prevent or lessen the severity of the common cold.

Since then, a slew of studies examining the health effects of vitamin C have produced conflicting results, fueling controversy and debate over whether vitamin C has any effect at all on the common cold.

A large analysis of previous studies on the possible protective effects of vitamin C, published in the Cochrane Database of Systematic Reviews in 2013, included studies that involved the use of at least 200 milligrams of vitamin C taken daily as either a preventative measure or treatment for the common cold.

The review found that endurance athletes or those exposed to extreme physical activities or low temperatures who may be deficient in vitamin C could benefit from a supplement. In fact, people in this category cut the incidence of colds by 50 percent by taking a daily dose of vitamin C.

Although that may be good news for marathon runners and Olympic skiers, the study found that for most people, vitamin C does not significantly reduce the risk of catching a cold.

However, researchers noted that taking regular vitamin C supplements while you're healthy could lessen the severity of your symptoms and help you get better more quickly if you do get sick. They found an 8 percent reduction in the duration of colds among adults and a 14 percent reduction among children taking at least 1 gram of vitamin C daily. They noted that this may be because of the antihistamine effect of the high-dose supplement.

The researchers also pointed out that most healthy adults get a cold only two or three times a year, so taking a large dose of vitamin C every day to slightly shorten the duration of only a few colds may not be the best approach. The study also showed that taking vitamin C only after cold symptoms appear does not affect the severity or duration of the illness.

"The failure of vitamin C supplementation to reduce the incidence of colds in the normal population indicates that routine mega-dose prophylaxis is not rationally justified for community use," the researchers concluded. "But evidence suggests that it could be justified in people exposed to brief periods of severe physical exercise or cold environments."

Cold Prevention Tips

Although taking vitamin C may not be a magical cure for colds or the key to cold prevention, you can take steps to protect yourself from these common viral infections.

Wash your hands often with soap and warm water. It's especially important to wash your hands after blowing your nose, sneezing, coughing, changing a diaper, or using the bathroom. And always wash your hands before you eat.

Avoid touching your eyes, nose, or mouth.

Steer clear of people who are sick, and stay at home if you have symptoms of a cold or the flu.

Avoid close contact with others.

Cover your mouth and nose when you cough or sneeze.

Immediately discard used tissues.

Regularly clean or disinfect surfaces and commonly shared objects, such as doorknobs, toys, and light switches.